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J Am Acad Child Adolesc Psychiatry. Author manuscript; available in PMC 2010 December 9.
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Published in final edited form as:
J Am Acad Child Adolesc Psychiatry. 2010 April ; 49(4): 397–405.
Pediatric Bipolar Disorder Versus Severe Mood Dysregulation:
Risk for Manic Episodes on Follow-Up
Argyris Stringaris, M.D., M.R.C.Psych., Argelinda Baroni, M.D., Caroline Haimm, B.A.,
Melissa Brotman, Ph.D., Catherine H. Lowe, M.S.W., Frances Myers, R.N., M.S.N., Eileen
Rustgi, Ph.D., Wanda Wheeler, M.S.W., Reilly Kayser, B.A., Kenneth Towbin, M.D., and
Ellen Leibenluft, M.D.
Mood and Anxiety Program, National Institute of Mental Health, Bethesda, MD
Abstract
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Objective—An important question in pediatric bipolar research is whether marked nonepisodic
irritability is a manifestation of bipolar disorder in youth. This study tests the hypothesis that
youth with severe mood dysregulation (SMD), a category created for the purpose of studying
children presenting with severe nonepisodic irritability, will be significantly less likely to develop
(hypo-)manic or mixed episodes over time than will youth with bipolar disorder (BD).
Method—Patients with SMD (N = 84) and narrowly defined BD (N = 93) at baseline were
followed up in 6-monthly intervals using the relevant K-SADS modules to ascertain (hypo-)manic
or mixed episodes.
Results—Only one of 84 SMD subjects (1/84 [1.2%]; 95% confidence interval CI = 0.0003 to
0.064) experienced a (hypo-)manic or mixed episode during the study (median follow-up = 28.7
months). The frequency of such episodes was more than 50 times higher in those with narrowly
defined BD (58/93 [62.4%]; 95% CI 0.52 to 0.72).
Conclusions—These data suggest that, over an approximately 2-year follow-up period, youth
with SMD are unlikely to develop (hypo-)manic or mixed episodes.
Keywords
bipolar disorder; pediatric; severe mood dysregulation; irritability; ADHD
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In American psychiatric clinics and inpatient settings, dramatic increases in the rates of
diagnosis of pediatric bipolar disorder (BD) have been documented over the past decade,1,2
with a concomitant increase in prescription rates for antipsychotic medication.3 This rapid
increase in the diagnosis of pediatric BD has coincided with the contention that the clinical
presentation of BD differs between children and adults.4,5
The debate regarding the pediatric presentation of BD is complex. One important aspect of it
has been the suggestion that marked irritability, even when it does not constitute an episodic
change from baseline, is a manifestation of BD in youth.4,6,7 To provide a framework for
research on whether irritable children without distinct manic episodes have a developmental
presentation of BD, we operationalized8 a clinical syndrome, severe mood dysregulation
Correspondence to Dr. A. Stringaris, Department of Child and Adolescent Psychiatry, Institute of Psychiatry, King's College London,
Denmark Hill, London, SE5 8AF United Kingdom [email protected].
Dr. Stringaris is currently based at the Institute of Psychiatry, King's College London, United Kingdom.
Disclosure: Drs. Stringaris, Baroni, Brotman, Rustgi, Towbin, and Leibenluft, and Ms. Haimm, Mr. Lowe, Ms. Myers, Ms. Wheeler,
and Mr. Kayser report no biomedical financial interests or potential conflicts of interest.
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(SMD), designed to capture chronically irritable children whose diagnostic status is in
doubt. This paper uses a longitudinal sample to investigate the extent to which subjects with
SMD develop episodes of (hypo-)mania, compared to youth with narrowly defined BD.
The criteria for SMD require a persistent, nonepisodic clinical presentation of negatively
valenced mood with frequent and impairing anger outbursts, combined with at least three of
the “B” criteria of mania (pressured speech, agitation, insomnia, and flight of ideas/racing
thoughts) and one (distractibility) that is also common to ADHD.8 A community-based
follow-up study suggests that SMD is common, with a lifetime prevalence of 3.3% in youth
9 to 19 years of age.9 Furthermore, in that sample SMD predicted depressive disorder at 7year follow-up in youths who were 9 to 19 years old at baseline.9 Consistent with this
finding, another community-based study of nonepisodic irritability in youth showed that it
predicted depressive disorders and generalized anxiety disorder, but not phobias, Axis II
disorders, or BD at 20-year follow-up.10 However, these studies were conducted in
community samples in which BD was a relatively rare outcome. Moreover, because the
intervals between assessments were long and depressive episodes are more frequent in adult
BD than are manic episodes,11 only depressive episodes may have been captured. For these
reasons, these studies allow only very limited inferences to be drawn about the relationship
between SMD or nonepisodic irritability and BD.
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The present study includes higher numbers of children with SMD and BD than commonly
afforded by epidemiologic samples, as well as data gathered at 6-month intervals over a
median follow-up of 28.4 months. The purpose of the study is to establish whether the
absence of (hypo-)manic episodes is an enduring characteristic of SMD, or whether children
commonly evolve from SMD to a more classic presentation of BD by developing episodes
of (hypo-)mania. If children with SMD differ markedly from BD in the frequency of manic
episodes, this would support the clinical importance of distinguishing children with severe
chronic irritability from those with classically defined BD. Accordingly, our hypothesis is
that, over time, children with SMD will be significantly less likely to experience a
(hypo-)manic or mixed episode than will those with BD.
Method
Participants
Participants with BD and SMD were enrolled in an Institutional Review Board-approved
study at the Intramural Research Program of the National Institute of Mental Health. Parents
and children provided written informed consent/assent.
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BD subjects met DSM-IV criteria for BDI/II, with a history of at least one clearly
demarcated hypomanic or manic episode (lasting ≥4 days for hypomania or ≥7 days for
mania). During these episodes, abnormally elevated or expansive mood, and at least three
DSM-IV criterion “B” mania symptoms were present.8
Participants with SMD fulfilled the following criteria: abnormal mood (specifically anger or
sadness), present at least half of the day on most days, and of sufficient severity to be
noticeable by people in the child's environment (e.g., parents, teachers, peers). In addition,
compared with his/her peers, the child exhibits hyperreactivity to negative emotional stimuli
(e.g., temper tantrums inappropriate for age or precipitating event) at least three times
weekly. In addition, SMD youth had hyperarousal symptoms (i.e., at least three of the
following: insomnia, intrusiveness, pressured speech, flight of ideas/racing thoughts,
distractibility, psychomotor agitation). Symptom onset had to be before age 12 years, and
symptoms were required to be present for at least 1 year, with no remission period ≥2
months. These symptoms were required to cause severe impairment in at least one setting
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(i.e., home, school, peers), and at least mild impairment in another. Euphoric mood or
distinct hypomanic or manic episodes lasting ≥1 day were exclusionary.8 Exclusion criteria
for both patient groups included IQ <70, pervasive developmental disorder, unstable medical
illness, or substance abuse within the past 2 months.
Initial Assessment
The Kiddie Schedule for Affective Disorders—Present and Lifetime Version (KSADSPL12), a semi-structured diagnostic interview was administered at the NIMH to parents and
children separately by graduate level clinicians with established reliability (κ = 0.9,
including the differentiation between SMD and BD). Clinicians administering the KSADS
were licensed practitioners (M.D., M.S.W., Ph.D., or M.S.N.) with 5 to 25 years of
postlicensure clinical experience. Training in KSADS consisted of 20 to 30 hours of
observation, monitored administration of the instrument, and establishing reliability with
experienced child research clinicians. Diagnoses were based on best-estimate procedures13
generated in a consensus conference led by a least one psychiatrist with extensive
experience evaluating children with bipolar-spectrum illness. SMD was assessed using a
specifically developed KSADS supplementary module.8,14
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The Wechsler Abbreviated Scale of Intelligence was used to measure intelligence15 at initial
assessment. WASI data were absent for five patients with SMD and one patient with BD.
For the WASI data, no imputation was used; the means and standard deviations presented
were calculated on those with data available, and group differences were estimated using
listwise deletion.
Longitudinal Data
After the initial in-person assessment, subjects were followed up, on average, at 6-month
intervals. Experienced clinicians with at least Master's-level qualifications and with
documented reliability on the KSADS administered the KSADS mania and depression
modules by telephone to the patient's parent. These KSADS modules were used to define the
onset, offset, and symptom content of manic, hypo-manic, mixed, or depressive episodes.
The initial telephone assessment is designated as “baseline” in this paper. The patients were
followed up subsequently in intervals of approximately 6 months; the means and standard
deviations (in parentheses) for the follow-up intervals are as follows: first follow-up: 6.02
(1.49) and 5.97 (2.35) months for SMD and BD, respectively; second follow-up: 6.06 (1.74)
and 5.51 (2.30) months for SMD and BD, respectively; third follow-up: 5.74 (1.83) and 5.54
(2.41) months for SMD and BD, respectively; and fourth follow-up: 6.06 (1.62) and 6.12
(1.99) months for SMD and BD, respectively.
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Figure 1 shows the data available at each time point and the attrition rates. Two things
should be noted when interpreting Figure 1. First, the denominator of the rates presented in
Figure 1 varies. This is because the study is ongoing and, therefore, not all patients enrolled
in the study at the same time point—by the time of data analysis, the range of possible
follow-up duration for a given patient varied from 6 to 30 months. Second, the numerator of
the rates provided in Figure 1 varies as a result of study attrition. Hence, the follow-up rates
are a quotient of the number of patients in the study at each follow-up point to the number of
patients who could have been followed up at that time point.
Statistical Analyses
Gender and comorbidity comparisons between SMD and BD were performed with χ2 tests.
To compare SMD and BD on age and IQ scores, t tests were used.
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To address the paper's main hypothesis comparing the rates of (hypo-)manic or mixed
episodes at follow-up between SMD and BD, we created a dichotomous variable that was
coded zero (0) if no manic, hypo-manic, or mixed episode had occurred, or one (1) if at least
one manic, hypo-manic, or mixed episode had occurred over the time of follow-up. The
respective proportions were estimated and binomial confidence intervals constructed around
those estimates. We conducted a z test of the null hypothesis that the proportion of SMD and
BD subjects experiencing at least one manic, hypo-manic, or mixed episode during the
follow-up period did not differ between groups. Of note, this analysis assumes that the
length of follow-up was equal between SMD and BD.
We also compared SMD and BD groups in the propensity to experience at least one
depressive episode during the follow-up period. The analytic strategy was similar to the one
for manic, hypo-manic, or mixed episodes. Finally, we used a t test to compare SMD and
BD on the mean number of depressive episodes over follow-up.
Only data from those available at the each study point were analyzed, and no imputation
procedure was used.
Results
Sample Characteristics
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For the follow-up study, 93 patients with BD and 84 patients with SMD had a baseline
assessment.
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The follow-up rates are shown in Figure 1, and the sample characteristics are described in
Table 1. At baseline, compared with youth with BD, participants with SMD were
significantly younger and more often male, although this did not reach statistical
significance. In addition, given the inclusion criteria for SMD, it is not surprising that
children with SMD showed higher rates of ODD and ADHD than did those with BD. BD
and SMD youth did not differ in the prevalence of CD or GAD. BD Type-I was present in
76% of the BD patients (71 of 93), the rest being BD Type-II. Retention rates over the
follow-up period of approximately 2 years were significantly higher for the BD than for the
SMD group. The median follow-up was 25.1 months overall (minimum = 0.7, maximum =
89.8), with a median of 23.0 months (minimum = 0.7, maximum = 75) for SMD and a
median of 32.3 months (minimum = 0.69, maximum = 89.8) for BD. The difference
between the two groups was significant (Mann–Whitney U = 2720, z = −3.48, p < .001). An
attrition analysis showed that not taking part in the study at the last follow-up was not
predicted by age, gender, IQ, or any of the following diagnoses: ODD, CD, ADHD, MDD,
or GAD (data available upon request).
Conversion from SMD to BD
The main hypothesis of this paper was that youth with SMD would be significantly less
likely to experience (hypo-)manic or mixed episodes over time, compared with BD. Of the
84 subjects with SMD at baseline who were followed up over time, only one experienced an
episode of mania or hypomania and thus was reclassified as BD. This subject, who had firstand second-degree relatives with BD, developed a brief hypomanic episode within 1 year of
enrollment in the study. Of the 93 subjects with BD followed up, 58 developed at least one
episode of mania, hypomania, or mixed state over the follow-up period. Therefore, the
probability of developing at least one manic, hypomanic, or mixed episode was
approximately 50 times lower among subjects with SMD (1/84 [1.2%]; 95% confidence
interval [CI] 0.0003 to 0.064) compared with subjects with BD (58/93 [62.4%]; 95% CI 0.52
to 0.72), and the difference was significant (z = −8.61; p < .00001). These results are
summarized in Figure 2. Given that the median follow-up differed significantly between
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groups, we wanted to ensure that we did not unduly bias our results in favor of our
hypothesis by having longer follow-up periods for BD than for SMD subjects. For this
reason, we conducted a supplementary analysis restricting the analysis to a maximum
follow-up of 75 months (the longest follow-up for SMD subjects) instead of 89.8 months
(the longest follow-up time BD subjects). This analysis showed that only one of 84 subjects
with SMD developed a (hypo-)manic or mixed episode during follow-up, whereas 50 of 85
subjects with BD (58.8%, 95% CI = 0.48 to 0.69) developed such an episode during followup (z = −8.16; p < .0001).
Episode Characteristics for SMD and BD
Table 2 displays the episode characteristics of the two groups. In BD, depressive episodes
were most common, followed by hypomanic episodes, as shown in Table 2. In addition, the
mean number of depressive episodes was significantly higher in BD than in SMD (Table 2).
Discussion
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We conducted a longitudinal follow-up study of a clinic sample of youth with SMD and
narrowly defined BD to answer an important question related to the pediatric BD debate—
namely, whether children commonly evolve from a phenotype characterized by severe,
nonepisodic irritability to a more classic presentation of BD by developing distinct episodes
of (hypo-)mania. We found that (hypo-)manic or mixed episodes were significantly less
likely to occur in youth with SMD compared with BD.
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It is important to note that SMD was created for the purpose of studying children presenting
with severe nonepidsodic irritability.8 SMD overlaps with ODD in that both ascertain
temper outbursts, irritability, and anger. Crucially, however, SMD does not include the
symptoms of defiance and annoyance that are also included in ODD—this distinction
between headstrong and irritable dimensions in ODD has been shown to have important
differential predictions.16,17 In addition, the criteria for SMD define irritability much more
specifically than do those for ODD, requiring a high frequency of outbursts, and the SMD
criteria require that impairing irritability be present in at least two settings, although a child
can meet criteria for ODD with impairment in only one setting. Thus, whereas most children
with SMD meet criteria for ODD, most with ODD do not meet criteria for SMD, and SMD,
but not ODD, ascertains a population that is as impaired as are youth with BD. For these
reasons, we undertook this line of research using the SMD criteria, rather than those for
ODD. Finally, it should be noted that SMD, as originally proposed,8 contains sadness as an
alternative to anger for the criterion of negatively valenced mood. Nonetheless, all SMD
youth meet the criteria of at least three outbursts per week, so that irritability is one of its
prominent features, regardless of whether the negatively valenced mood is anger or sadness.
One of the main questions about SMD relates to the extent to which it is a developmental
presentation of BD. If it were, one would expect that, over time, youth with SMD would
manifest manic or hypomanic episodes meeting DSM-IV criteria. However, only one of 84
SMD subjects manifested an episode of (hypo-)mania at follow-up. The difference between
SMD and BD is of an order of magnitude: the probability for a (hypo-)manic episode
occurring in BD subjects was more than 50 times higher than in those with SMD. Moreover,
the lower confidence limit of the probability of a (hypo-)manic episode in BD was more
than six times higher than the upper confidence limit for manic episodes in SMD.
Our finding that only one youth with SMD experienced an episode of (hypo)mania over the
follow-up period contrasts with the high conversion rate for short-episode bipolar disorder–
not otherwise specified (BD-NOS) noted in the Course and Outcome of Bipolar Illness in
Youth (COBY) study.18 The diagnosis of BD-NOS is poorly specified in DSM-IV; in child
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psychiatry, it is frequently assigned to two distinct clinical presentations: youth with severe,
nonepisodic irritability (a presentation that we operationalized as SMD), and those with
distinct (hypo-)manic episodes that are shorter than 4 days in duration. This distinction
between these different presentations is important, given its potential implications for
pathophysiology treatment, and nosologic classification. Youth with the short-duration
episodes were followed longitudinally in the COBY study, in which approximately 25% of
the BD-NOS subjects experienced a full-duration hypomanic or manic episode over the
course of a 3-year follow-up18 In contrast, in the present study, 1.2% of SMD subjects
converted from SMD to BD-I or BD-II within an approximate 2-year follow-up. Of note, the
AACAP guidelines for BD recommend considering both the “short episode” and the
“nonepisodic” phenotypes to be BD-NOS presentations.19 In contrast, our data, in concert
with those from the COBY study, suggest that, whereas the “short-episode” phenotype may
be a manifestation of BD and thus may warrant the diagnosis of BD-NOS, such a conclusion
is considerably less clearly justified in the case of the nonepisodic presentation that is
characteristic of SMD. Importantly, our study did not include youth with brief (hypo-)manic
episodes, like those in the COBY study. Because we included only the SMD phenotype (i.e.,
severe, nonepisodic irritability), our data do not speak to the longitudinal course of any of
the other possible bipolar spectrum phenotypes.
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Our finding here is consistent with previous results using SMD-proxy phenotypes in
community samples9,10 as well as with a preliminary family history study.20 These studies
indicate that irritable youth are at risk for developing depressive and anxiety disorders in
adulthood, and that youth with SMD are less likely than those with BD to have a parent with
BD.20 Moreover, our findings are in keeping with those of a recent clinic study showing
that, for children with severe persistent irritability, a diagnosis of BD is rarely justified upon
careful clinical assessment.21 However, it should be noted that the current study was not
designed to test the hypothesis that the occurrence of (hypo-)manic or mixed episodes in
SMD was no more than would occur by chance; this would require a much larger sample.
Moreover, our findings do not exclude the possibility that BD and SMD have common
pathophysiologic features. Indeed, previous studies suggest that the two share behavioral
deficits in emotion labeling processing14,22 and cognitive flexibility,23 although the neural
mechanisms mediating these deficits may differ between the two patient groups.24
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In sum, to the extent that the question, “Is SMD a developmental presentation of BD?” is
framed categorically, the conclusion from this and previous studies9,20,24 is “no.” Because
treatment decisions are categorical, there is value to framing the question categorically. That
is, if a clinician views SMD as a BD phenotype, that clinician might prescribe atypical
antipsychotic and/or mood-stabilizing medication for youth with this clinical presentation.
Alternatively, if the clinician views SMD as a phenotype of anxiety and/or unipolar
depression, coupled with ADHD, that individual might consider prescribing antidepressant
medication coupled with a stimulant (these are medications that are relatively
contraindicated in BD). Unfortunately, no published data currently exist on the safety or
effectiveness of anti-depressant or stimulant medication in the SMD phenotype, and that is
an important question for future study. So far, the only clinical trial in SMD is a pilot study
of lithium, which was not effective.25 Additional treatment trials in youth with severe,
nonepisodic irritability are a pressing public health need, given that an SMD proxy
phenotype occurred with a prevalence of 3.3% in an epidemiologic sample in the United
States9 and mood lability occurred in more than 5% of the population of children and
adolescents in a sample in the United Kingdom.26
Although it is important to frame the question, “Is SMD a developmental presentation of
BD?” categorically, it is equally important to ask the question dimensionally. Recent data
demonstrate convincingly that DSM-IV diagnoses may not necessarily be
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pathophysiologically distinct: there is considerable genetic overlap between BD and
schizophrenia27 and between BD and MDD.28 As noted, BD and SMD appear to share
pathophysiological mechanisms, making it possible that the SMD phenotype will ultimately
be placed on a pathophysiological spectrum between BD and MDD and/or other depressive
syndromes. Accordingly, we found that depressive episodes were significantly more
common in the BD group; a possible post hoc explanation for this finding is that, consistent
with previous data,10 SMD may be linked with depressive phenotypes not characterized by
episodicity, such as dysthymia. The findings of this study are relevant to researchers who
study the early development of BD and inform their choices for the phenotypes to use, for
example in genetic studies of early onset BD.
This study has a number of strengths. It is the first to report a follow-up of subjects with
well-characterized SMD. Moreover, in comparison with previous community-based studies
on SMD9 and mood lability,20 in which BD and SMD are relatively rare, the present clinic
sample is enriched with cases of both SMD and BD and thus in reducing the likelihood of
recall bias.
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However, there are a number of important limitations. First, there is considerable attrition.
Therefore, we cannot exclude the possibility that the conversion rate from SMD to BD has
been underestimated. Secondly, from a psychometric point of view, it is conceivable that the
prominence of nonepisodic irritability in those with SMD has generated “background noise”
affecting on our instrument's ability to detect episodes. Although we cannot exclude this
possibility, the effect size of the difference between SMD and BD is very large and therefore
unlikely to be the result of a reduced signal-to-noise ratio. Third, it was not feasible to have
the follow-up assessments be conducted blindly, so assessment bias cannot be excluded.
However, follow-up was performed by experienced clinicians, who were 1) particularly
attuned to the clinical importance of establishing (hypo-)manic and mixed episodes and 2)
instructed to have a low threshold for their ascertainment. Importantly, parents were aware
that, should an SMD child develop manic or hypomanic symptoms, the child and his/her
family could continue to participate in the study, so that there should be no concern that
reporting such an episode would result in exclusion. Fourth, follow-up interviews were only
conducted only with the patient's parents and not with the children themselves. Given the
generally low parent–child agreement in reporting symptoms of mania and depression, this
may conceivably underestimate symptoms.29,30 However, we consider it unlikely that fullblown (hypo-)manic or mixed episodes would have gone unnoticed by parents. Fifth, it is
important to reiterate that this study focuses on the comparison between narrowly defined
BD and only one phenotype of several that have been described as BD–NOS. That is,
although SMD captures children with nonepisodic irritability, this study did not include
children with episodes of manic symptoms that are too short to meet DSM-IV criteria for
hypomania. Thus, clinicians and researchers should not extrapolate from these results to
other BD-NOS presentations, in particular to children with episode durations of less than 4
days. Finally, we used a narrow phenotype to ascertain cases of BD at baseline, in that we
required abnormally elevated or expansive mood during an episode; the presence of
irritability on its own30,31 was not a sufficient Criterion A for (hypo-)mania in this study. It
is therefore possible that the BD cases in this study might not be representative of all cases
of pediatric BD. However, two findings argue against this. First, the patterns of our results
regarding the course of BD are in keeping with those of a recent large longitudinal study,32
i.e., episodes of depression were most common. Second, a recent study comparing patients
with BD and abnormally elevated or expansive mood and/or grandiosity as the only
Criterion A to those with either episodic irritability-only or with episodes characterized by
both irritability and elevated or expansive mood suggests these groups are similar on
important variables.33
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In conclusion, our results suggest that research efforts should continue to focus on the
pathophysiology of SMD and BD, as well as on the treatment of both conditions, given that
both groups continued to exhibit significant psychopathology. In addition, studies should
address the overlap and distinctions between SMD and ODD. Finally, studies using larger
samples with longer follow-ups of SMD subjects, replicated in other centers, are required.
Acknowledgments
This work was supported by the National Institute of Mental Health, Intramural Program.
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FIGURE 1.
Percentage of patients with severe mood dysregulation (SMD) and bipolar disorder (BD) at
each follow-up point is shown in the bars. Note: Underneath each pair of bars are the raw
number proportions for each category.
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FIGURE 2.
Bars with standard errors show the percentage of patients with either severe mood
dysregulation (SMD) or bipolar disorder (BD) who developed a (hypo-)manic or mixed
episode during the follow-up period.
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TABLE 1
Sample Characteristics at Baseline
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SMD
BD
t
χ2
84
93
–
–
Mean age (SD)
11.6 (2.3)
12.9 (2.8)
−3.2**
–
Gender (male)
56 (66.7%)
49 (52.7%)
Mean IQ (SD)
101.9 (13.3)
107.8 (15.2)
−2.6**
ADHD (%)
69 (82.1%)
42 (45.2%)
–
25.8***
ODD (%)
66 (78.6%)
24 (25.8%)
–
49.2***
N
CD (%)
3.6§
–
4 (4.8%)
2 (2.22%)
–
0.9
GAD (%)
25 (29.8%)
30 (32.3%)
–
0.128
MDD (%)
19 (22.6%)
–
–
–
Note: ADHD = attention-deficit/hyperactivity disorder; BD = bipolar disorder; CD = conduct disorder; GAD = generalized anxiety disorder; MDD
= major depressive disorder; ODD = oppositional defiant disorder; SMD = severe mood dysregulation.
**
p < .01;
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***
p < .001;
§
p = .058.
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0–0.28
0–6
0–0.23
0–14
0–0.21
0–2
0–0.09
Hypomanic per months in study
Manic
Manic per months in study
Depressive
Depressive per months in study
Mixed
Mixed per months in study
p < .001.
0–12
Range
0.005 (0.015)
0.18 (.49)
0.05 (0.056)
2.18 (2.71)
0.016 (0.04)
0.59 (1.23)
0.036 (0.05)
1.34 (1.96)
Mean (SD)
BD (N = 93)
Hypomanic
Number of episodes
Characteristic
***
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TABLE 2
–
–
0–0.34
0–4
–
–
–
–
Range
–
–
0.015 (0.046)
0.36 (0.83)
–
–
–
–
Mean (SD)
SMD (N = 84)
−5.2***
t Test
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Episode Characteristics for Severe Mood Dysregulation (SMD) and Bipolar Disorder (BD)
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